Fiber optic components are used in a wide variety of applications. The use of optical fibers as a medium for transmission of digital data (including voice, internet and IP video data) is becoming increasingly more common due to the high reliability and large bandwidth available with optical transmission systems. Fundamental to these systems are optical subassemblies for transmitting and/or receiving optical signals.
Optical subassemblies typically comprise an interposer. As used herein, an interposer functions as a substrate for optical, opto-electrical, and electrical components and provides interconnections to optically and/or electrically interconnect the optical/opto-electrical/electrical components. Generally, although not necessarily, the axis of the opto-electric devices (OEDs) and that of the fiber tend to be perpendicular when mounted in the interposer. Accordingly, the interposer serves not only to optically couple the OED and the fiber, but also to bend the light to effect the coupling.
There is a general need to simplify both the design and manufacture of interposers. To this end, a new type of interposer has been introduced in which the electrical components, including the OED, are on one side of the interposer, while the optical conduit is mounted on the other side. This configuration avoids the need for vias to provide an electrical path from one side of the interposer to the other because all the OEDs, associated circuitry and electrical interconnects are located on the same side of the interposer.
Although an interposer configured with the optical conduit on one side and electronics on the other simplifies manufacturing, it does pose its own challenges. For example, as mentioned above, an interposer generally needs to bend/turn the light perpendicularly between the OEDs and the fibers. To this end, separate molded light turning elements are typically used to bend the light between the OED and the fibers. Unfortunately, these light turning elements tend to be expensive to manufacture, and are relatively time consuming to incorporate onto the interposer as they must be both aligned and bonded to the substrate. Additionally, because these light turning elements are separate/discrete components which are independently molded and handled, they require a certain mass to provide the necessary strength and size to facilitate molding and handling. Consequently, these elements tend to be relatively bulky and add considerable height to the interposer. This is particularly problematic because interposers are often used in space-restricted situations in which height must be minimized. Thus, not only are the light turning elements expensive to prepare and complicated to install, but they also add undesirable height to the interposer.
Therefore, there is a need for an interposer configuration that avoids the need for discrete light turning elements that must be aligned and bonded to the substrate. The present invention fulfills this need among others.